crawford



(No Model.) 2 Sheets-Sheetl.

R. CRAWFORD. AIR HEATER.

No. 578,095. Patented Mar, 2, 1897.

nro/mir (N0 MGeL) 2 Sheets-Sheet 2- R. CRAWFORD.,

AIR HEATER.

N0. -.578,095. l yPatented Map2, 1897.

IN VEN TUR wmvEssEs I v f er )array/Er TM: Nom'us PETERS ou. MTD-mwa. WASHINGTON, D. c.

` UNITED STATES ROBERT CRAWFORD,

PATENT CEEICE.v

OE NEW YORK, N. Y.

AIR-HEATER.

SPECIFICATION forming part of Letters Patent No. 578,095, dated March 2, 1897. Appnmitn inea July 13,1896. Seriana. 598,916. (Nomad.)

T0 all whom, t may concern:

Be it known that I, ROBERT CRAWFORD, of the city, county, and State of New York, have invented certain new and useful Improvements in Air-Heaters, of which the following is a specification.

My invention relates to that class of airheaters which are intended to utilize the waste heat which is ordinarily discharged into the smoke-flue after the blast has done its work in aboiler; and the particulars of my improvements are hereinafter more fully set forth.

In the drawings, Figure l is a side View of my improved heater, the brick ilues at either end being shown in section. Fig. 2 is a view of the heater in the same position as in Fig. l with the side plates removed. Fig. 3 is a top view with the top plates removed, the top iianges of the longitudinal and transverse partitions being removed for clearness in showing the other parts. Fig. 4 is an end view with the partitions ff removed, and Fig. 5 is a detail showing the way in which the transverse air-pipes are secured in position.

Similar letters of reference designate similar parts in al1 the iigures.

A indicates the main flue above a returnflue tubular boiler, and B is the opening into the smoke-stack. Between these I place my improved heater, which I prefer to make in several sections, as C D E, formed from angle-plates of thin metal, detachably secured together by means of bolts, as shown. The last section E is intended to make the connection with the smoke-stack and is provided with a damper e to regulate the draft. In the following parts of this specification I shall refer to the sections C and D, unless I particularly specify the section E. Within the heater I place two longitudinal partitions F G, one near each side, whereby the interior is divided into three. sections, of which the central one is much the wider. The ends of the smaller sections are closed by partitions ffff, and intermediate partitions or deilectors g g' g2 are placed at suitable distances. The partitions F Gr are provided with openings in staggered lines, and through these extend series of pipes t' t' t' 1l, which are threaded upon their ends and are held in place by lock-nuts wrm n, by which a tight joint is secured between the pipes and partitions. It will be seen that by this construction it is practicable to secure a ready and true adjustment between the pipes and the partitions and to make effective and tight joints.

M is the fresh-air inlet, and N the outlet.

The waste heat traveling from the flue A to the smoke-stack B passes through the central division of the heater among the pipes c' c' t' z', which, in consequence, become heated.

The fresh air entering through the pipe M 'passes into the first division of the heater between the side and the partition F. The partition fand deiiector g confine the current laterally, and, under the influence of natural or artificial draft, it is directed through the first series of pipes t' 0I il 1l to the other side of the heater. 'lhepartition g' causes the current to return through the neXt series of pipes c' t' t' t', when it is again deiiected by the partition g2 and finally reaches the discharge-pipe N, from whence it may be distributed in the usual manner.

The capacity of either of the lateral sections of the air-flues is greater than the combined capacity of the series of pipes emptying into it or out of it, so that an alternately rapid and divided and slower and united current is established,which is quicker where the heat isv greater and slower where it is less. This passing and repassing of the air through the severalseries of pipes results in raising it to a high temperature, and the breaking up of the currents in the intermediate chamber at the ends of the pipes tends by mixing the air to produce uniformity of temperature in the whole volume and to prevent unequal expansion and contraction of the heater or scorching or burning in spots.

In the bottoms of the sections C D E, I place hand-holes covered by slides Z Z Z2, bymeans `of which the sections can be cleaned and kept free from ashes and soot.

In this manner I secure a heater which is simple, strong, and very eective. It can be transported in a knockdown condition and can be readily put together by unskilled labor. A greater or less number of sections may be used, according to the available space and other conditions. The number of transverse pipes may be varied by simply plugging'the unused holes by running the lock-nuts upon short solid bolts instead of on the pipes. The

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interior is readily accessible through the hand-holes Z Z Z2 for cleaning. The partsvbeing detachable, any portion of the heater can be removed for repairs, and the pipes can be taken out and replaced.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-

An air-heater formed of several sections built up of angle-plates detachably secured together by means of bolts, provided with intermediate longitudinal partitions forming between them a main fiue and forming between them and the adjacent Walls of the heater air-ilues, series of pipes in each sec- 15 tion disposed across the same in staggered lines provided With threaded ends and detachably secured in said partitions by means of lock-nuts,said air-lines connecting through said pipes and provided With transverse par- 2o titions to deflect the air-current alternately from one flue to the other through the several series of air-pipes, substantially as described.

ROBERT CRAWFORD.

WVitnesses:

WM. D. N EILLEY, CRoMWELL CHILDE. 

